Vehicle occupant restraint belt retractors have heretofore been provided with an inertia responsive pendulum or the like for pivoting a lock bar into engagement with a pair of toothed ratched plates attached to the ends of the belt reel so that the length of a restraint belt extending from the reel is fixed to restrain an occupant upon the vehicle seat. The locking engagement between the lock bar and the ratchet plate teeth is effectively maintained for as long as an occupant restraining load is imposed on the belt even though the inertia stimulus is terminated. When the load is removed from the belt, a slight belt rewinding rotation by a reel windup spring permits gravity to pivot the lock bar out of engagement from the ratchet plates to permit subsequent belt unwinding.
It is known to use the aforedescribed seat belt retractor in a seat belt system of the type having one end of the belt connected to the vehicle door so that the belt will be automatically moved to an unrestraining position when the door is opened and returned to the restraining position when the door is closed. It has been recognized as desirable to provide a buckle in the belt so that the belt can be disconnected to permit opening movement of the door. It has also been recognized as desirable to provide a handle which is manually operable to forcibly disengage the lock bar from the ratchet plates so that the belt may be unwound.
One arrangement for effecting disengagement of the lock bar is to pivotally mount the lock bar on the retractor housing via a collapsible support means normally supporting the lock bar in proximity with the ratchet plates and having a collapsed condition to bodily withdraw the lock bar from engagement with the ratchet plates. Copending patent application Ser. No. 044,753, now U.S. Pat. No. 4,218,033, Bernard J. Finn et al, filed June 1, 1979, is an example of such a lock bar release device.
U.S. Pat. No. 3,771,814, issued Nov. 13, 1973 to Hahn, discloses a retractor wherein a manually operable handle is connected to one end of the lock bar adjacent one of the ratchet plates and is operable to manually pivot the lock bar out of engagement with both of the ratchet plates. It is characteristic of this lock bar release arrangement that the lock bar must have a high level of strength to resist twisting thereof by the high level of torque necessary to disengage the lock bar from the ratchet plates during imposition of a relatively large occupant restraining load on the reel via the restraint belt. Furthermore, the pivotal mount between the lock bar and the retractor frame must be configured to provide a fulcrum for supporting the lock bar for pivotal movement under imposition of occupant restraining load thereon.
It is also known in seat belt retractors to mount the lock bar on the retractor via a plastic pendulum support member as disclosed in U.S. Pat. No. 4,129,267, issued Dec. 12, 1978 to Degras et al, and assigned to the assignee of this invention. The plastic pendulum support consistently and accurately locates the lock bar relative the axis of reel rotation and yields to permit load sustaining engagement of the lock bar with the retractor housing. A disadvantage of the plastic pendulum support member is that the lock bar fulcrum provided thereby does not have sufficient strength to support the lock bar for pivotal movement by a manually operable handle attached to one end thereof.